Patent attributes
A communication unit comprises a command signal generator for generating a command signal. A transmitter transmits communication signals at one of two frequencies and for transmitting the command signal. A receiver receives communication signals at one of the two frequencies and for receiving the command signal. Upon initiation of the command signal, the command signal is transmitted for receipt by all active units in the system and the unit transmitting the command signal receives communication signals at a selected frequency of the two frequencies and transmits communication signals at another frequency. Upon reception of the command signal from another unit in the system, the unit receiving the command signal transmits a communication signal at the selected frequency of the two frequencies and receives communication signals at the another frequency.
